Medical countermeasures are required to address the emerging radiological and nuclear threats. In 2005-2006, the National Institute of Allergy and Infectious Diseases (NIAID), biodefense and related program, and Armed forces Radiobiology Research Institute (AFRRI), a premier DOD Radiobiology Research Institute, established an Interagency agreement to facilitate discovery and development of radiation countermeasures. These agents were derived from pharmaceutical companies, industry, and scientists from Institutions of higher learning and tested in mouse model against injury from cobalt-60 gamma ionizing radiations at AFRRI. Several classes of compounds (~40) such as nutraceuticals (vitamin E isomers), growth factors (Granulocyte Colony Stimulating Factor [unreadable]G-CSF), signal transduction agents, and immunomodulators have been evaluated since 2006-present.